1. Field of the Invention
This invention relates to a process for drying a moving textile web which is wet with a fluorocarbon liquid having dispersed therein a textile agent.
2. Description of the Prior Art
German Pat. No. 2,002,286 discloses the padding of a textile material with a solution or suspension of a dye in a liquid of the formula R-F wherein R is a radical of the formula FCl.sub. 2 C--CFCl-- , Cl.sub. 3 C--, Cl.sub.2 HC-- or F.sub.2 ClC-- CFCl-- . Thereafter, the textile material is dried, for example, by drawing air through it, and the dye is fixed by conventional fixation methods. Belgian Pat. No. 760,243 discloses a continuous process for drying and fixing a moving textile material which is padded with a solution or a dispersion of colorant in an organic solvent which forms vapors heavier than air. Solvent vapors obtained by evaporation from the web are superheated and returned to contact the textile material so as to evaporate the solvent from the material. U.S. Pat. No. 3,542,506 discloses squeeze roll expression from a textile web of dye liquor comprising a liquid vehicle, such as trichlorotrifluoroethane, followed by countercurrent application of superheated steam, to evaporate the vehicle and sweep resultant vapors from the web, and recovery of the vehicle by decantation of the condensed mixture of steam and vapors of the vehicle. Junginger in Verfahrenstechnik 4 (1970) No. 2, 66-73 discloses that migration of dissolved substances in textile wetting liquids is maximum at a drying rate of about 10 kg./meter.sup.2 /hour; various drying means are disclosed. Gerber in Melliand Textilberichte [English Edition], March, 1972, p. 283 et seq. (Melliand Textilberichte, March, 1972, p. 336 et seq.) discusses the problem of dye migration during intermediate drying and notes that it should be possible to prevent migration by shock drying but that the necessary evaporation rates of over 100 kg./meter.sup.2 /hour cannot be obtained with conventional convection dryers. Organic solvents, such as tetrachloroethylene, are suggested as offering an advantage in this respect. Lehmann et al. in Textil-Praxis Internat. 28:52-54, 53 (1973) disclose that although the evaporation rate of perchloroethylene is ten to eleven times greater than that of water, which puts it into the range of an evaporation capacity of 100 kg./meter.sup.2 /hour, theoretical considerations and experiments have demonstrated that migration using perchloroethylene as a dyeing medium is much greater than when water is used. Finally, Capponi et al. in American Dyestuff Reporter, January, 1974, page 47, in a discussion of continuous dyeing with solvents, disclose that migration during dyeing must be controlled by mechanical engineering methods and that evaporation of the solvent must not take place too quickly so that migration can largely be prevented.